Improvement in crank movements



H. 0. BRADFORD.

Crank-Movements.

No.135,073. y Patenredjamznms.

Fay. e.

,m mom-umomAm/c ca Mmmm/:Is mom) UNITED STATES PATENT OFFICE.

HORACE C. BRADFORD, OF PROVIDENCE, RHODE ISLAND.

IMPROVEMENT IN CRANK MOVEMENTS.

Specification forming part of Letters Patent No. 135,073, dated January 2l, 1873.

To all lwho-m it may concern:

Be it known that I, HORAGEG. BRADFORD, of the city and county of Providence, in the State of Rhode Island, have invented a cerembody a crank-arm, which is mounted on and revolves with a face-plate, and which depends for its automatic radial movement to and from the axis of the face-plate upon a center-pin, which, while it revolves on its own axis, is otherwise stationary, and around which eccentrically the face-plate on its own axis is revolved. My invention consists in combining with the automatic reciprocating crank-arm, the centerpin, and face-plate a certain semi-elliptic auxiliarybearin g, which constitutes a connectingmedium between the crank-arm and the face-plate, whereby the strain and wear on the centerpin are greatly lessened, the several parts rendered correspondingly more durable, and the general efticiency of the machine with which it is employed materially augmented; and I do .herebydeclare that ythe following specication, taken in cdnne'ction with the drawing furnished and forming a part of the same, is a clear and true description of my invention, and a practical method of applying the same to a machine with which it has a fully-demonstrated value.

Referring to the drawing, Figure 1 represents in elevation the frame and bed of a handplaner provided with my improved quick-re` side. In this instance the arm-is shown as if provided with an adjustable slotted crank-pin connection. D denotes the face-plate. It is in this instance combined with and is in fact a part of the driving-gear, with which the pinion a on the hand-crank shaft b engages. E denotes the pitman, which connects the crankarm with the sliding bed B. The crank-arm C is united to the face-plate D, and the latter is secured to its axis d by the center-pin F, which passes loosely through the axis d and the face-plate, and is rmly fastened to the crank-arm. rlhe parts as lthus far described and arranged resemble certain quick-return crank motions which have been applied to hand-planers constructed by me for several years past, and they, therefore, involve no features of patentable novelty. It will readily be understood that by revolving the face-plate gear the crank-arm C will be carried with it, after the manner of the usual crank-arm; also, that during every complete revolution the crank-arm will be automatically advanced and withdrawn from and to the center of the axis around which the face-plate revolves; and al so that the extent of the radial movement of the crank arm depends solely upon the distance between the true axis of the center-pin and the face-plate axis dyand, still further, that all the strain of the crank movement must necessarily be borne by the center-pin F. It will also be readily understood that the outer end of the crank-arm will alternately be swung first in advance of the movement of the faceplate and then behind the said movement, and

that'this rocking is effected on the steady-pin c, which loosely engages with a slot in the crank-arm. The inner end of the crank-arm during every revolution of the face-plate also describes a line which may be described as the upper half of an ellipse divided longitudinally, as illustrated in Fig. 4. The semi-elliptical groove f is cut in the side of the face-plate gear, in lines corresponding with the throw 7 of the end of the crank-arm and also with its radial movement. The crank-arm has a projecting pin, h, on its rear side, whichenters and loosely occupies the groove f in the faceplate. The entire portion of the semi-elliptical groove is traversed by the pin h during every revolution of the face-plate. The curved portion of the slot corresponds fully with the through the inner end of the crankarm, whichv is to subsequently receive the pin h. A carefully-pointed instrument, exactly fitting said hole, is then inserted therein, and made to bear against the side of the face-plate while the plate is revolved. By this means the true centerline of the groove will be described. In building new machines, of course, the groove, however determined, can be cast' in the faceplate and subsequently finished.

It will be readily observed that the pin h and the groove can be made to perform a portion of the labor heretofore solely devolvin g upon the center-pin, and that the crank-arm is more evenly held to the face-plate while at work than if the strain was borne entirely by the center-pin.

'The construction of the pin and groove may be somewhat varied and still produce the same practical results. For instance, instead of the groove in the face-plate a raised semi-elliptical cam-edge may be employed, with a bifurcated swiveled pin to embrace it instead of the simple pin h. I do not, therefore, limit myself to the precise construction shown, as the semi-elliptical auxiliarybearings constitute the novel feature of my invention.

Having thus described my invention, Iclaim as new and desire to secure by Letters Patent- The combination ofthe semi-elliptical auxiliary bearings f h with the rotary face-plate, the automatically reciprocating crank-arm, its cen ter-pin, and steady-pin, substantially as and for the purposes specified.

HORACE C. BRADFORD.

Vitnesses:

HENRY MARTIN, JOHN C. PURKIs. 

